Superheroes of the Human Microbiota and Beyond: an introduction to Mechano-Micro-Biology.
Each of us has, in all likelihood, more bacterial cells in us and on us than our own cells. While scientists have studied bacteria free swimming in liquid for centuries, we have come to realize more recently that most bacteria live attached to surfaces and each other in dense communities called biofilms. One of the most ubiquitous biopolymers that mediates those interactions is called Type IV pilus. These extraordinary polymers are a few nanometers in width and can extend to length of tens of microns while undergoing cycles of extension and retraction. We will show here how physical forces generated by Type IV pili between bacteria and between bacteria and surfaces control bacteria motility, aggregation and ultimately physiology. From motility to antibiotic resistance, bacterial physical forces have emerged as a key factor. This is one more example where physics can help illuminate biology and maybe biology inspire physics.